The map above shows Illinois and Oklahoma side by side at exactly the same scale, using equal-area projections, so their true relative sizes are preserved.
Illinois vs Oklahoma Geography
Land area
- Illinois has a land area of 55,513 square miles (143,778 km²), while Oklahoma has 68,597 square miles (177,665 km²).
- Oklahoma's land area is 1.2 times (24%) larger than Illinois'.
Total area
- Illinois: 57,913 square miles (149,995 km²) vs Oklahoma: 69,899 square miles (181,038 km²), including inland and coastal water.
- Oklahoma's total area is 1.2 times (21%) larger than Illinois'.
Length
- Illinois is 390 miles (628 km) long from north to south; Oklahoma is 533 miles (857 km).
- Oklahoma's north-south length is 1.4 times (37%) longer than Illinois'.
Width
- Illinois spans 283 miles (456 km) east to west; Oklahoma spans 490 miles (789 km).
- Oklahoma's east-west width is 1.7 times (73%) wider than Illinois'.
Highest point
- Illinois's highest point is Charles Mound at 1,232 feet (376 m); Oklahoma's is Black Mesa at 4,980 feet (1,518 m).
- Black Mesa is 3,748 feet higher than Charles Mound.
Lowest point
- Illinois's lowest point is Mississippi River at 292 feet; Oklahoma's is Little River at 289 feet.
- Oklahoma's lowest point is 3 feet lower.
Illinois vs Oklahoma Population and History
Population
- Illinois has a population of 12,710,158 (2024), while Oklahoma has 4,095,393 (2024).
- Illinois' population is 3.1 times (210%) larger than Oklahoma's.
Population density
- Illinois: 229.0 people per square mile vs Oklahoma: 59.7.
- Illinois' population density is 3.8 times (284%) higher than Oklahoma's.
Biggest city
- Illinois's biggest city is Chicago with 2,721,308 people; Oklahoma's is Oklahoma City with 712,919.
- Chicago's population is 3.8 times (282%) larger than Oklahoma City's.
Largest metro area
- Illinois's largest metropolitan area is Chicago-Naperville-Elgin, IL-IN metro area (9,408,576 people) vs Oklahoma's Oklahoma City, OK metro area (1,497,821).
- Chicago-Naperville-Elgin, IL-IN metro area's population is 6.3 times (528%) larger than Oklahoma City, OK metro area's.
History
- Illinois: Admitted to the Union on December 3, 1818, as the 21st state.
- Oklahoma: Admitted to the Union on November 16, 1907, as the 46th state.
- In its current form, Illinois is the older of the two by 89 years.
Illinois vs Oklahoma Economy
GDP
- Illinois's GDP is $1,148.1 billion (2024) vs Oklahoma's $263.7 billion.
- Illinois' economic output is 4.4 times (335%) larger than Oklahoma's.
GDP per capita
- Illinois: $90,330 per person vs Oklahoma: $64,388.
- Illinois' GDP per capita is 1.4 times (40%) higher than Oklahoma's.
Average income
- Illinois: $74,522 vs Oklahoma: $63,708 average income per person (per capita personal income).
- Illinois' average income is 1.2 times (17%) higher than Oklahoma's.
Illinois vs Oklahoma Counties
Number of counties
- Illinois has 102 counties, while Oklahoma has 77.
- Illinois' county count is 1.3 times (32%) higher than Oklahoma's.
Biggest county by area
- Illinois's largest county is McLean County at 1,183 square miles; Oklahoma's is Osage County at 2,247 square miles.
- Osage County's land area is 1.9 times (90%) larger than McLean County's.
Smallest county by area
- Illinois: Putnam County (160 sq mi) vs Oklahoma: Marshall County (372 sq mi).
- Marshall County's land area is 2.3 times (132%) larger than Putnam County's.
Most populous county
- Illinois: Cook County (5,182,617 people) vs Oklahoma: Oklahoma County (816,490 people).
- Cook County's population is 6.3 times (535%) larger than Oklahoma County's.
Least populous county
- Illinois: Hardin County (3,550 people) vs Oklahoma: Cimarron County (2,133 people).
- Hardin County's population is 1.7 times (66%) larger than Cimarron County's.
Richest county
- Illinois: Cumberland County ($104,890 per capita income) vs Oklahoma: Washington County ($126,749).
- Washington County's income is 1.2 times (21%) richer than Cumberland County's.
Poorest county
- Illinois: Lawrence County ($43,606 per capita income) vs Oklahoma: Atoka County ($38,709).
- Lawrence County's income is 1.1 times (13%) richer than Atoka County's.
Illinois vs Oklahoma Taxes
State income tax
- Illinois has a top income tax rate of 4.95%, while Oklahoma has a top income tax rate of 4.5%.
- Illinois's top rate is 0.45 percentage points higher.
Property tax
- Illinois: 1.92% effective rate vs Oklahoma: 0.75% of home value per year.
- Illinois's rate is 1.17 percentage points higher.
Sales tax
- Illinois: 8.98% combined state and average local rate vs Oklahoma: 9.06%.
- Oklahoma's combined rate is 0.08 percentage points higher.
Official Websites
Illinois official website · Oklahoma official website
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More Size Comparisons
All Illinois size comparisons · All Oklahoma size comparisons
Area, elevation and boundary figures come from official national statistics and US Census Bureau and Natural Earth boundary data; US state population, economic, county and tax figures come from the US Census Bureau, the Bureau of Economic Analysis and the Tax Foundation. Figures are rounded and for general reference.